This invention relates to a coolant recycling apparatus for converting used coolant, such as coolant for liquid-cooled engines, into fresh coolant having a quality equivalent to that of newly manufactured coolant.
The great majority of automotive vehicles, including trucks and passengers vehicles, employ liquid-cooled engines in which heat is removed from the engine by circulating a liquid coolant through a water jacket formed in the engine. The most common liquid coolants are mixtures of water and a cooling agent in the form of a glycol (ethylene glycol or propylene glycol). The ratio of water to glycol in the coolant will depend on the desired boiling and freezing points of the coolant, but is generally on the order of 50% water and 50% glycol by volume. The coolant usually also contains additives, generally referred to as inhibitors, which prevent rust corrosion and scaling inside the water jacket of an engine, water pump, radiator, and wherever else coolant is present in the cooling system for an engine.
Over long periods of use, the liquid coolant in an engine becomes contaminated with debris, rust, dirt, acids, metals, and corrosion products from the inside of the engine or radiator. Some of these contaminants decrease the cooling capacity of the coolant and others are harmful to metal portions of the cooling system. Furthermore, some of the inhibitors in the coolant deteriorate over time. When a coolant becomes contaminated or depleted, it is conventional to drain out the old coolant and replace it with a fresh coolant mixture. In many instances, the old coolant is simply discarded, either in land fills or directly into the sewer system. Since some glycols (particularly ethylene glycol) are toxic, and since the used coolant may contain lead and other metals produced by corrosion, the discarding of used coolant poses environmental problems. Furthermore, much of the glycol in used coolant is still perfectly usable as a coolant, so the discarding of used coolant represents a significant waste of valuable resources.